In LTE (Long Term Evolution) standardized in 3GPP (3rd Generation Partnership Project) which is a standardization organization for radio communication systems, there are applied SON (Self Organizing Network) techniques in which a radio base station autonomously adjusts its parameters (referred to below as base station parameters) without human intervention (see Non-Patent Document 1, for example).
As one of the SON techniques, there is proposed a method by which base station parameters (such as handover parameters) defining coverage are adjusted according to load information exchanged between radio base stations in order to balance loads between the radio base stations. Such an optimization technique is referred to as MLB (Mobility Load Balancing). Note that coverage means a logical or physical communication area of a radio base station.
Specifically, in an LTE system, the following four classes of load information are defined. (a) Usage of PRBs (Physical Resource Blocks) being units for time-frequency resource allocation, (b) load of backhaul between a radio base station and a core network, (c) hardware load of a radio base station, and (d) capacity class being an index of relative communication capacity of a radio base station, and a ratio of available communication capacity to the communication capacity.